The present invention relates to a data-imprinting camera that is capable of imprinting data on a roll film wound by a manual operation.
The data-imprinting camera imprints photographing data such as a shutter speed, an aperture value or a date on an area outside a picture area of a roll film. A data imprinting device of the camera includes a light emitting unit for exposing the film to form a two dimensional pattern as the imprinting data.
There are two types of the data imprinting devices. The first type device is an one-shot exposure data imprinting device that is provided with a two dimensional light emitting device to form the two dimensional pattern at one exposure timing. The one-shot exposure data imprinting device is relatively large in size, and therefore the device is mounted on a back cover of the camera to expose the film from behind, i.e., from the back surface of the film that is opposite to an image forming surface.
The second type device is a scanning exposure data imprinting device that is provided with a plurality of light emitting diodes (LED's) arranged on a line perpendicular to the winding direction of the film. The LED's are controlled in synchronism with the winding of the film to sequentially form the two dimensional pattern. The scanning exposure data imprinting device is relatively small in size, and therefore it can be mounted on the back cover as well as the one-shot exposure data imprinting device or on a side of the aperture to expose the front surface of the film that is the same as the image forming surface.
A medium-format camera using a Brownie film (120 film) is provided with the scanning exposure data imprinting device. Since the Brownie film has a baking paper on the back surface thereof, the data imprinting device must project the light pattern from the front side of the film. Accordingly, the scanning exposure data imprinting device is used for the medium-format camera.
In the scanning exposure data imprinting device, light emissions of the LED's are controlled in synchronism with pulses that are generated corresponding to the film winding.
However, since the scanning exposure data imprinting device imprints the pattern in synchronism with the film winding, the film winding at the constant speed forms the proper pattern, while the variation of the winding speed disturbs to form the proper pattern. That is, when the camera is provided with a motor drive winding mechanism, the scanning exposure data imprinting device imprints the proper pattern, while a manual winding mechanism may disturbs to form the proper pattern.
Particularly, when a film wind lever is manually operated with short, quick operations, which breaks correspondence between the pulse interval and the film winding speed. For instance, when the film is rapidly wound and then stopped by the manual operation, the pulse generating mechanism generates over-pulse due to inertial moment, which makes the data imprinting device continue the data imprinting onto the stopped film, overlapping the plural exposures on the same position. For instance, when the LED's of the data imprinting device are controlled to form the pattern of "8", the pattern of "8" is formed on the winding film as shown in FIG. 8A, while the pattern of "1" is formed on the stopped film as shown in FIG. 8B due to multiple exposure.